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EFFECTS OF ULTRAVIOLET-B IRRADIATION ON PLANTS DURING MILD WATER STRESS. 1. EFFECTS ON DIURNAL STOMATAL RESISTANCE
Citation:
Teramura, A., M. Tevini, AND W. Iwanzik. EFFECTS OF ULTRAVIOLET-B IRRADIATION ON PLANTS DURING MILD WATER STRESS. 1. EFFECTS ON DIURNAL STOMATAL RESISTANCE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-83/037 (NTIS PB84102524), 1983.
Description:
Cucumber (Cucumis sativus L. cv. Delikatess) and radish (Raphanus sativus L. cv. Saxa Treib) were grown in a factorial design under two ultraviolet-B (UV-B) irradiances and three levels of water stress. On a weighted, daily dose basis the UV-B radiation treatments were equivalent to ambient levels during the beginning of the growing season (controls) and those predicted for an 11.6% ozone depletion during the summer solstice at 49 deg. N latitude. Water stress was achieved by varying the frequency of watering. The combination of UV-B radiation and water stress resulted in large species differences in the pattern of stomatal resistances. This study indicated that Cucumis is one of the most sensitive crop species to UV-B radiation yet identified and that the primary effect of UV-B radiation in this species is a decrease in the leaf diffusive resistance to water vapor. This, therefore, may result in reductions in growth via increased water stress.